article: It?s always hard to say goodbye to someone you love. In Washington DC, US, local   zoo-goers are sad about the news that their superstar panda Tai Shan is going to leave the National Zoo.
  At a morning meeting on December 4, zoo director  Steven Montfort said that the black-eared bear would be going off to China sometime over the winter, under an agreement with the Chinese government.
  Tai Shan, whose name means "peaceful mountain," was born at the DC zoo on July 9, 2005. He has been loved by zoo-goers since his first public show in December of that year.
  But under the agreement that brought his mother, Mei Xiang, and father, Tian Tian, to the zoo from China, all three belong to   China.
  Tai Shan should have been returned to China when he was 2. But China gave him two extensions   to stay at the National Zoo. Tai is old enough to breed  . So it?s time for him to come back to China and join a program to try to increase the panda population.
  The National Zoo has tried to breed Mei Xiang a few times since Tai Shan was born, without success. Montfort said the zoo would try again soon in the hope of producing another baby panda. "We?re hopeful every year," he said.
question: According to the passage, who is going to leave the National Zoo?
options: Steven Montfort. Mei Xiang. Tian Tian. Tai Shan.